Yes, it is. Flashget is a very nice download manager.
The speed thing just utilizes your bandwidth better, giving you a faster overall download. For example, you try to download a file from a server. You open a connection and start downloading the file at 10kb/s, which is the max speed the server allows. Your max dl speed is 60kb/s. But if you use flashget, then it say splits your download into 6 pieces. It then opens 6 connections to the server, each being the 10kb/s allowed by the server, giving you a total download speed of 60kb/s.

But it doesn\'t actually make you download at 200kb/s or summin, which is what most people believe when they read it first.